I recently discovered a cover for the song "Kokoronashi" on SoundCloud, so I tried to find the original version of the song, or at least information about who the original artist is, on Youtube.

However, this song seems to have been covered by so many different people so many times that I cannot find out who sang the original as some singers who covered it cite conflicting original versions/artists of this song.

(The search queries that I performed on Youtube were "kokoronashi", "kokoronashi original)

I noticed that the picture above was almost always associated with this song on Youtube and it had an anime artstyle, so I imagine that it might be some anime song, but upon performing a reverse image search, all the results simply brought me to the Youtube covers that contain the picture instead of pointing me to an anime where I can find the original song.

Does anybody know who sang the original version of this song and/or what anime it comes from, if any?

I realize that this is a very vague description of a song since I only provide the name, but I guarantee that if you search "kokoronashi" on Youtube, you will find many covers of the song that I am referring to without trouble on the very first search results page.

If it helps, here is a link to a fairly popular English cover of the song. I did not link to a Japanese cover because they tend to be more likely to be taken down by Youtube due to copyright violations than English covers, but the English melodies are very much the same as the Japanese covers that I have seen.